1. Technical Field
The present invention relates to an image processing apparatus, image recording apparatus, image processing method, and recording medium storing an image processing program.
2. Background Art
Conventionally, GS1-128 (EAN-128) is used as a high-density barcode. The total length of the GS1-128 barcode including quiet zones on both sides needs to be within 60 mm, and the GS1-128 comprises lines of four different widths.
In printing such a barcode at a resolution of 300 dpi, both a white line (hereinafter referred to as a white bar) and a black line (hereinafter referred to as a black bar) are printed with 2 dots (0.169 mm), 4 dots, 6 dots, and 8 dots. In printing such a barcode at a resolution of 600 dpi, both the white bar and the black bar are printed with 4 dots (0.169 mm), 8 dots, 12 dots, and 16 dots. In printing such a barcode at a resolution of 1200 dpi, both the white bar and the black bar are printed with 9 dots (0.190 mm), 18 dots, 27 dots, and 36 dots. However, in this case, the line width is very narrow, and high-precision printing is necessary to make the barcode readable.
To satisfy this kind of requirement, a technology that corrects the barcode width (e.g., JP-2010-091590-A) and a technology that makes increases the resolution in a barcode area (e.g., JP-2009-272667-A) have been proposed.
However, a problem for both these approaches is that, in general, dots formed using an inkjet printer tend to bleed. Therefore, in printing a barcode using an inkjet printer, the amount of ink liquid used for printing each pixel increases at low print resolutions, resulting in more bleeding of the dot. Consequently, the black bar becomes wider than it would be at a higher print resolution, and that makes the barcode unreadable.
In addition, in some cases, the width of black bar is corrected when the barcode is printed by an inkjet printer. The problem is that the correctional unit is itself large since the correction is performed in units of dot. Consequently, the width of a narrow black bar cannot be corrected properly, and that also makes the barcode unreadable.